This training and research award will prepare the candidate for an independent career as a molecular and behavioral neuroscientist using rigorous behavioral tesfing and genefic manipulafions to analyze the brain circuits underlying learning and memory. The candidate is an experimental psychologist with significant experience in the area of animal learning. In the training (K99) phase of the award, which is now complete, the candidate (1) developed laboratory skills in molecular genetics and quantitative microscopy;(2) expanded his knowledge of molecular genefics and translational neuroscience so that he can independently develop novel scientific ideas, integrate his research findings with exisfing knowledge, and relate them to clinical practice;(3) developed a strong understanding of the ethical issues inherent in the pracfice of science;and (4) secured a tenure-track faculty position at a major research university. The independent (ROO) phase of the award will provide support as the candidate establishes an independent research program aimed at elucidafing mechanisms through which adult hippocampal neurogenesis contributes to learning and memory. The adult hippocampus retains the ability to generate neurons, and a rapidly growing literature documents that adult-born neurons are funcfionally significant. The candidate has shown, for instance, that blocking hippocampal neurogenesis using irradiafion or an inducible genefic method impairs contextual fear condifioning, a ubiquitous form of learning in which organisms acquire fear of environments that predict harm. Using contextual fear conditioning as a model system, the proposed research will use targeted irradiation and genetic manipulations to analyze how adult-born neurons contribute to acquisition, retenfion, and retrieval of memories.